U.S. patent number 8,018,172 [Application Number 12/386,123] was granted by the patent office on 2011-09-13 for method and apparatus for led dimming.
This patent grant is currently assigned to MAGTECH Industries Corporation. Invention is credited to Itai Leshniak.
United States Patent |
8,018,172 |
Leshniak |
September 13, 2011 |
Method and apparatus for LED dimming
Abstract
A dimmable LED driver provides accurate full range dimming for
LED lighting. The driver utilizes the timing of an AC signal rather
than its power output or other characteristics to accurately
determine the level of light a user desires. In this manner, the
driver provides accurate full range dimming without the need for
calibration to specific AC power levels. The driver may detect the
period of an AC signal allowing the driver to be used with various
frequencies without the need for calibration. In one or more
embodiments, the driver compares the pulse widths of a dimmed AC
signal to the period of the AC signal to determine the desired
light level. The driver may comprise a signal processor and
controller in one or more embodiments.
Inventors: |
Leshniak; Itai (Henderson,
NV) |
Assignee: |
MAGTECH Industries Corporation
(Las Vegas, NV)
|
Family
ID: |
42933834 |
Appl.
No.: |
12/386,123 |
Filed: |
April 13, 2009 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20100259183 A1 |
Oct 14, 2010 |
|
Current U.S.
Class: |
315/194; 315/291;
315/246 |
Current CPC
Class: |
H05B
45/37 (20200101); H05B 45/10 (20200101); Y02B
20/30 (20130101) |
Current International
Class: |
H05B
37/02 (20060101) |
Field of
Search: |
;315/DIG.4,291,294,295,246,247,209R,224,225,194,195 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Vu; David Hung
Attorney, Agent or Firm: Weide & Miller, Ltd.
Claims
What is claimed is:
1. An LED driver comprising: an input configured to accept an AC
signal; a rectifier in electrical communication with the input, the
rectifier configured to rectify the AC signal into a pulse train
comprising one or more pulses; a comparator in electrical
communication with the rectifier, the comparator configured to
utilize a voltage threshold whereby the comparator outputs a first
signal while a voltage of the one or more pulses is above the
voltage threshold and outputs a second signal while the voltage of
the one or more pulses is below the voltage threshold; a controller
in electrical communication with the comparator, the controller
configured to determine a pulse width of the one or more pulses and
a period of the AC signal from the first signal and the second
signal whereby the controller is configured to determine a desired
level of light output based on a ratio of the pulse width to the
period and generate an output signal configured to provide the
desired level of light output through LED lighting; and an output
configured to provide the output signal to the LED lighting.
2. The LED driver of claim 1 further comprising a lighting can
having a socket for accepting the LED lighting whereby the output
is in electrical communication with the socket, the LED lighting
comprising a LED bulb.
3. The LED driver of claim 1 further comprising a voltage reference
configured to provide the voltage threshold, the voltage reference
in electrical communication with the comparator.
4. The LED driver of claim 1, wherein the controller determines the
pulse width of the one or more pulses based on the duration of the
first signal in relation to the second signal from the
comparator.
5. The LED driver of claim 1, wherein the first output and the
second output of the comparator form a square wave comprising one
or more square pulses whereby the duration of the one or more
square pulses is the pulse width of the one or more pulses and a
time between corresponding portions of the one or more square
pulses is the period of the AC signal.
6. The LED driver of claim 1, wherein the controller is configured
to utilize a preset value for the period of the AC signal rather
than determining the period of the AC signal.
7. An LED driver comprising: an input configured to accept an AC
signal from a dimmer; a controller configured to compare a voltage
of the AC signal to a voltage threshold to determine a pulse width
of the AC signal whereby the controller outputs an output signal
based on the ratio of the pulse width to a period of the AC signal
to provide a desired level of light output through one or more
LEDs, the period of the AC signal being at least one preset value
stored in the LED driver; and an output configured to provide the
output signal to the one or more LEDs whereby the output signal
travels through the output to the one or more LEDs.
8. The LED driver of claim 7 further comprising a lighting can
having a socket for accepting the one or more LEDs whereby the
output is in electrical communication with the socket.
9. The LED driver of claim 7 further comprising a signal processor
coupled with the input and the controller, the signal processor
configured to rectify the AC signal into a pulse train comprising
one or more pulses whereby the controller is configured to compare
a voltage of the one or more pulses to the voltage threshold to
determine the pulse width and period of the AC signal.
10. The LED driver of claim 7, wherein the controller determines
the pulse width by comparing the voltage of the AC signal to the
voltage threshold whereby the pulse width is delineated at a first
point by the voltage of the AC signal increasing across the voltage
threshold and at a second point by the voltage of the AC signal
decreasing across the voltage threshold, the pulse width being the
time between the first point and the second point.
11. The LED driver of claim 7, wherein the controller sets the
period of the AC signal to the at least one preset value closest to
a detected period of the AC signal whereby the controller
determines the detected period of the AC signal by comparing the
voltage of the AC signal to the voltage threshold, wherein the
period is measured by the time between the voltage of the AC signal
crossing the voltage threshold a first time and the voltage of the
AC signal crossing the voltage threshold in the same direction a
consecutive time.
12. A method for dimming an LED comprising: accepting an AC signal
from a dimmer at an input of a dimmable LED driver; comparing one
or more voltages of the AC signal to a voltage threshold to
determine one or more points where the one or more voltages cross
the voltage threshold; identifying one or more pulse widths of one
or more pulses in the AC signal, the one or more pulse widths
delineated by the time between at least two of the one or more
points; identifying a period of the AC signal; determining a
desired level of light output based on a ratio between the one or
more pulse widths and the period; and based on the ratio,
generating an output signal to provide the desired level of light
from one or more LEDs.
13. The method of claim 12 further comprising processing the AC
signal by rectifying the AC signal with a signal processor.
14. The method of claim 12, wherein the one or more voltages are
compared to the voltage threshold by a comparator of the dimmable
LED driver, the voltage threshold being provided by a voltage
reference in electrical communication with the comparator.
15. The method of claim 12, wherein the one or more pulse widths of
the one or more pulses in the AC signal and the period of the AC
signal is identified by a controller of the dimmable LED driver
whereby the desired level of light output is determined by the
controller based on the ratio of the pulse width and period.
16. The method of claim 12 further comprising dimming the AC signal
with the dimmer, the dimmer having an adjustable control.
17. The method of claim 12, wherein the pulse width is the time
between at least two consecutive points of the one or more
points.
18. The method of claim 12, wherein identifying the period of the
AC signal comprises selecting at least one preset value stored
within the dimmable LED driver to be the period of the AC
signal.
19. The method of claim 12, wherein identifying the period of the
AC signal comprises identifying the time between at least two of
the one or more points whereby a first point of the at least two
points is where the voltage of the AC signal increases across the
voltage threshold a first time and a second point of the at least
two points is where the voltage of the AC signal increases across
the voltage threshold a consecutive time.
20. The method of claim 12, wherein identifying the period of the
AC signal comprises identifying the time between at least two of
the one or more points whereby a first of the at least two points
is where the voltage of the AC signal decreases across the voltage
threshold a first time and a second of the at least two points is
where the voltage of the AC signal decreases across the voltage
threshold a consecutive time.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally light dimmers and in particular to
a method and apparatus for dimming LED lighting.
2. Related Art
Phase dimmers are commonly used to dim incandescent lights in
residential and commercial applications. Such dimmers generally
operate by chopping the sine wave of an AC signal thereby reducing
the energy output to dim one or more lights. While this allows an
incandescent bulb to be dimmed, a phase dimmer's output is not well
suited for LED lighting.
The phase dimmer's output must generally be converted into a signal
that can drive an LED light source. One method has been to convert
the dimmed power output of a phase dimmer into a corresponding
signal for an LED light source. Traditionally, this conversion has
resulted in workable dimming of LED lighting via a phase dimmer.
However, the conversion results in dimming of lesser quality than
that of incandescent lighting. For example, a phase dimmer can not
smoothly dim an LED light source from high or maximum brightness
down to low or no brightness.
LED lighting is increasingly popular and highly desirable due to
its high efficiency light output. LED lighting may also be more
compact and have a longer life than incandescent or other types of
lighting. Unfortunately, traditional dimming systems do not allow
LEDs to be dimmed in the way incandescent or other lighting
technologies can be. This prevents LEDs from being considered for
use or used where dimming is desired.
From the discussion that follows, it will become apparent that the
present invention addresses the deficiencies associated with the
prior art while providing numerous additional advantages and
benefits not contemplated or possible with prior art
constructions.
SUMMARY OF THE INVENTION
A dimmable LED driver which provides full range dimming of LED
lighting is disclosed herein. The dimmable LED driver accurately
determines the desired level of light output from an AC input
signal by utilizing the timing of the AC signal, and provides light
output from one or more LEDs accordingly. As will become apparent
from the discussion herein, the dimmable LED driver has numerous
advantages over traditional LED drivers which utilize power level
to determine the desired level of light output.
In one embodiment, the dimmable LED driver comprises an input, a
rectifier, a comparator, a controller, and an output. The input may
be configured to accept an AC signal which is dimmable to produce a
desired level of light. The rectifier may be in electrical
communication with the input and configured to rectify the AC
signal into a pulse train comprising one or more pulses.
The comparator may be in electrical communication with the
rectifier and may be configured to utilize a voltage threshold. The
comparator may output a first signal while a voltage of the one or
more pulses is above the voltage threshold and output a second
signal while the voltage of the one or more pulses is below the
voltage threshold. The voltage threshold, such as a constant
voltage, may be provided by a voltage reference in electrical
communication with the comparator.
In some embodiments, the first output and the second output of the
comparator form a square wave comprising one or more square pulses.
In these embodiments, the duration of the one or more square pulses
may be the pulse width of the one or more pulses and the time
between corresponding portions of the one or more square pulses may
be the period of the AC signal.
The controller may be in electrical communication with the
comparator and may be configured to determine a pulse width of the
one or more pulses and a period of the AC signal from the first
signal and the second signal. The controller may also utilize one
or more preset values for the period of the AC signal. In these
embodiments, the period need not be determined. The controller may
determine the desired level of light output based on a ratio of the
pulse width to the period and generate an output signal to provide
the desired level of light output through LED lighting. The output
signal may comprise pulse width modulation signals and current
change signals in one or more embodiments.
The controller may function in various ways. For example, the
controller may determine the pulse width of the one or more pulses
based on the duration of the first output and the second output
from the comparator.
The output may be configured to electrically couple to the LED
lighting so that the output signal travels through the output to
the LED lighting. In one embodiment, the dimmable LED driver may
include a lighting can having a socket for accepting LED lighting,
such as an LED bulb. In this embodiment, the output may be in
electrical communication with the socket.
In one embodiment, the dimmable LED driver comprises an input
configured to accept an AC signal, a controller, and an output
configured to electrically couple to one or more LEDs to allow an
output signal to reach the one or more LEDs.
The controller may be configured to compare a voltage of the AC
signal to a voltage threshold to determine a pulse width of the AC
signal. The controller may determine a desired level of light
output based on the ratio of the pulse width to a period of the AC
signal and generate the output signal which provides the desired
level of light output through one or more LEDs. The period of the
AC signal may be a preset value stored in the dimmable LED
driver.
In some embodiments, the pulse width may be delineated at a first
point by the voltage of the AC signal increasing across the voltage
threshold and at a second point by the voltage of the AC signal
decreasing across the voltage threshold. In these embodiments, the
pulse width may be the time between the first point and the second
point. Also, the period may be measured by the time between the
voltage of the AC signal crossing the voltage threshold a first
time and the voltage of the AC signal crossing the voltage
threshold in the same direction a consecutive time.
Similar to the above, this embodiment may include additional
elements. For example, the dimmable LED may comprise a lighting can
having a socket for accepting the one or more LEDs. The output of
the LED driver may be in electrical communication with the socket.
In addition, the dimmable LED driver may include a voltage
reference configured to provide a constant voltage which the
controller may utilize as the voltage threshold. A rectifier
coupled with the input and the controller may be provided as well.
The rectifier may be configured to rectify the AC signal into a
pulse train comprising one or more pulses. In this embodiment, the
controller may be configured to compare a voltage of the one or
more pulses to the voltage threshold to determine the pulse width
and period of the AC signal.
A method for dimming one or more LEDs is also provided. In one
embodiment, the method may comprise accepting an AC signal at an
input of a dimmable LED driver, and comparing one or more voltages
of the AC signal to a voltage threshold to determine one or more
points where the one or more voltages cross the voltage threshold.
A pulse width of one or more pulses in the AC signal delineated by
the time between at least two of the one or more points may be
identified along with a period of the AC signal. In this manner, a
desired level of light output based on the ratio between the pulse
width and the period may be determined, and an output signal may be
generated to provide the desired level of light from one or more
LEDs. The one or more voltages may be compared to the voltage
threshold by a comparator of the dimmable LED driver with the
voltage threshold being provided by a voltage reference in
electrical communication with the comparator.
The pulse width of the one or more pulses in the AC signal and the
period of the AC signal may be identified by a microprocessor of
the dimmable LED driver whereby the desired level of light output
is determined by the microprocessor based on the ratio of the pulse
width and period. The pulse width may be the time between at least
two consecutive points of the one or more points.
The period may be identified by the time between at least two of
the one or more points whereby a first point of the at least two
points is where the voltage of the AC signal increases across the
voltage threshold a first time and a second point of the at least
two points is where the voltage of the AC signal increases across
the voltage threshold a consecutive time. Likewise, the period may
also or alternatively be identified by the time between at least
two of the one or more points whereby a first of the at least two
points is where the voltage of the AC signal decreases across the
voltage threshold a first time and a second of the at least two
points is where the voltage of the AC signal decreases across the
voltage threshold a consecutive time. It is noted that in some
embodiments, the period may be identified by one or more preset
values for the period of the AC signal.
Additional steps of some embodiments of the method include dimming
the AC signal with a phase dimmer having an adjustable control.
Also, the method may include providing the output signal to the one
or more LEDs through a socket of a lighting can.
Other systems, methods, features and advantages of the invention
will be or will become apparent to one with skill in the art upon
examination of the following figures and detailed description. It
is intended that all such additional systems, methods, features and
advantages be included within this description, be within the scope
of the invention, and be protected by the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The components in the figures are not necessarily to scale,
emphasis instead being placed upon illustrating the principles of
the invention. In the figures, like reference numerals designate
corresponding parts throughout the different views.
FIG. 1 is a block diagram illustrating an exemplary wiring diagram
for an exemplary dimmable LED driver;
FIG. 2A illustrates an exemplary AC signal at a low level of
dimming;
FIG. 2B illustrates an exemplary AC signal at a moderate level of
dimming;
FIG. 2C illustrates an exemplary AC signal at a high level of
dimming;
FIG. 3A illustrates a pulse width measurement and period
measurement for an exemplary AC signal at a low level of
dimming;
FIG. 3B illustrates a pulse width measurement and period
measurement for an exemplary AC signal at a moderate level of
dimming;
FIG. 3C illustrates a pulse width measurement and period
measurement for an exemplary AC signal at a high level of
dimming;
FIG. 4A is a block diagram illustrating elements of an exemplary
dimmable LED driver;
FIG. 4B is a block diagram illustrating elements of an exemplary
dimmable LED driver;
FIG. 4C is a block diagram illustrating elements of an exemplary
dimmable LED driver;
FIG. 5A illustrates a pulse train of an exemplary AC signal at a
low level of dimming;
FIG. 5B illustrates a pulse train of an exemplary AC signal at a
moderate level of dimming;
FIG. 5C illustrates a pulse train of an exemplary AC signal at a
high level of dimming;
FIG. 6A is a cross section view of an exemplary lighting can having
a dimmable LED driver; and
FIG. 6B is a perspective view of an exemplary LED bulb having a
dimmable LED driver.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following description, numerous specific details are set
forth in order to provide a more thorough description of the
present invention. It will be apparent, however, to one skilled in
the art, that the present invention may be practiced without these
specific details. In other instances, well-known features have not
been described in detail so as not to obscure the invention.
LED lighting, such as one or more LED based bulbs or one or more
individual LEDs themselves, typically requires an adapter or driver
which converts a 115V, 230V, 277V, or other AC power source to a DC
source which is usable to properly power an LED. This is because
LEDs are not typically designed to operate with AC power directly.
Typically, a driver also provides a level of current and voltage
within the operating parameters of an LED to ensure proper
operation of the LED. For example, a driver may accept an AC power
input and provide a relatively low voltage DC output to power an
LED.
The dimmable LED driver herein is generally configured to accept an
AC input signal or AC power and to provide an output for powering
LED lighting. Though the LED lighting is generally discussed herein
in terms of one or more LEDs, it will be understood that the
dimmable LED driver may be used with a variety of light emitting
devices that utilize one or more LEDs for their light source. For
example, individual LEDs or LED based light bulbs may be powered by
the dimmable LED driver.
The dimmable LED driver allows full range (0% to 100% light output)
dimming for LED lights. The dimmable LED driver also allows a
desired level of light to be accurately provided by LED lighting.
The desired level of light or light output as used herein refers to
the level of light a user desires for a room, building, or other
interior or exterior space. In general, a user indicates his or her
desired level of light by interacting with a lighting control, such
as a dimmer as will be discussed below.
In general, the dimmable LED driver utilizes the timing or phase of
an AC input signal to determine a user's desired level of light
output. This is highly advantageous in that utilizing the timing of
an AC input allows the desired level of light output to be
accurately determined.
In contrast, traditional LED drivers utilize the power level of an
AC power source to determine the desired level of light output. In
general, this works by measuring the difference between the actual
AC output and the normal or reference output of an AC power source
to determine the light level that is desired. For example, an AC
output of half an AC power source's reference or normal output
would indicate that half of the maximum light level should be
provided. A traditional LED driver would then adjust its output
accordingly to provide half the maximum light output from a
LED.
In practice however, the use of power level to determine the amount
of dimming is difficult or impossible to properly implement. This
is because it is difficult, if not impossible, to accurately
establish a reference power output for an AC power source. As is
known, AC power supply will change as a function of voltage
depending on the AC power source. For instance, in North America a
standard wall outlet may provide 110-120V at 60 Hz while other
voltage and frequency standards are utilized elsewhere.
AC power sources (including those providing power according to a
standard) rarely produce a constant output. For example, in North
America, utility companies may change supply voltages by up to 10%.
Thus, a residential outlet may ideally output 115V, but its output
may somewhat abruptly change from anywhere between 110V and 120V.
Further, turning on or off electrical devices can cause
fluctuations in power levels. For example, AC power output often
fluctuates when appliances, air conditioning units, or other high
power draw devices are activated. While traditional LED drivers may
be calibrated or set to expect reference power outputs according to
AC power standards, this calibration cannot compensate for these
real time changes to power output.
Without an accurate or reliable reference power output, the
determination of desired light level by a traditional LED driver is
inaccurate. This is because the comparison of actual power output
to an inaccurate reference power output skews the determination of
the desired light level. For example, if the expected reference
power output is set lower than the actual reference power level of
an AC power source, the LED driver may provide light output higher
than what is desired. Where the expected reference power output is
set higher than the actual reference power level, the LED driver
may provide light output lower than what is desired.
Some manufacturers have attempted to compensate for the known
inaccuracy of the reference power output by reducing dimming range.
For example, a LED driver may be configured such that AC power
output below a certain threshold turns off a light while AC power
output above a certain threshold results in maximum brightness. In
this manner light output may be dimmed/increased between the
thresholds. However, this is a limited range and often results in
the light abruptly turning off as AC power output is lowered, and
the light abruptly jumping to maximum output as AC power output is
increased. In some installations, traditional LED drivers cause LED
lighting to remain on even when a user desires no light, or cause
LED lighting to jump to a maximum level when a moderate level of
light is desired, as light levels are adjusted.
These abrupt changes in light level and reduced dimming range are
undesirable especially when LED dimming is compared to that of
incandescent or other lighting technologies. In many applications,
the inability to smoothly dim LED lighting may overwhelm its
benefits, including durability, efficiency, and reliability,
leading users to select older lighting technologies. In contrast,
the dimmable LED driver herein provides full range dimming from
100% to 0% light output without abrupt changes in light level
unless desired by the user.
The dimmable LED driver will now be described with regard to the
figures. FIG. 1 is a block diagram illustrating a dimmable LED
driver 104 connected to a phase dimmer 112, and an AC power source
120. The LED driver 104 may have one or more outputs 116 which are
used to power an LED bulb 108 or other LED lighting. It is noted
that, though shown with a single LED bulb 108, an LED driver 104
may drive a plurality of LED bulbs 108 or other LED lighting.
The block diagram of FIG. 1 illustrates a standard or typical
wiring setup for a phase dimmer 112 and AC power source 120. For
this reason, the wiring configuration may be found in the vast
majority of phase dimmer 112 installations. Accordingly, it can be
seen that the dimmable LED driver 104 may be used to retrofit
existing wiring for fully dimmable LED lighting. In addition, it
can be seen that the dimmable LED driver 104 does not require
special wiring setups in order to provide full range LED dimming.
This is highly advantageous because the power efficiency,
reliability, and durability benefits of LED lighting can be
conveniently provided with full range dimming.
As will be described further below, the LED driver 104 may accept
an AC signal from an AC power source 120 which may be altered by a
dimmer 112. For example, as shown, the AC signal from the AC power
source 120 passes through the dimmer 112 before reaching the
dimmable LED driver 104. The dimmer 112 may alter the duty cycle of
the AC signal to control the power provided by the AC signal.
Traditionally, this alteration in the duty cycle allows the voltage
of an AC signal to be controlled which allows light output from
incandescent lighting to be controlled. In contrast, with the
dimmable LED driver 104 herein, the changes or alterations to the
AC signal caused by the dimmer may be detected to determine and
ultimately provide a corresponding level of light output through an
LED bulb 108, as will be described further below.
It is noted that the changes in the AC signal may be used to
determine desired characteristics of light output in addition to or
instead of the level of light output. For example, alterations to
the duty cycle of an AC signal may be used to determine the desired
color temperature or color of light output. For example, rather
than dimming one or more LEDs, the LED driver herein may change the
color temperature or color of light output based on the detected
alterations to an AC signal. Of course, in one or more embodiments,
the LED driver may be configured to control the level of light
output, color temperature, or a combination thereof based on
alterations to the AC signal.
Generally, a dimmer 112 allows a user to alter the output signal of
an AC power source by adjusting a control 124. In the embodiment
shown, for example, a sliding control may be moved linearly to
increase or decrease the output signal's power level. Of course,
other types of controls may be used. For example, the dimmer 112
may have a rotary knob that can be rotated to control the output of
an AC power source. Generally, moving the control in one direction
increases power output while moving in the opposite direction
decreases power output.
In one or more embodiments, the dimmer 112 may be a phase dimmer. A
phase dimmer 112 generally operates by altering the duty cycle of
an AC signal to control the power level of the AC signal. For
example, portions of the voltage of an AC signal may chopped, such
as by zeroing out the voltage or setting the voltage to another low
level. To illustrate, FIGS. 2A-2C show the sine wave of an AC
signal that has been altered by chopping portions of the signal. As
can be seen, instead of a smooth sine wave, the altered signals
have zero or other low voltage portions.
As illustrated the sine waves have been chopped at their trailing
edges. In some dimmers, signal chopping may occur on the leading
edges of a sine wave. For example, a dimmer utilizing a triac may
chop the leading edges of an AC signal rather than the trailing
edges. It will be understood that the dimmable LED driver herein
may determine a desired level of light and thus dim one or more
LEDs regardless of whether an AC signal has been chopped at its
leading or trailing edges.
Typically, an AC signal will be chopped at substantially the same
place or places within each period of the wave for a particular
level of dimming. This is shown in FIGS. 2A-2C where similar or the
same portions of the AC signal have been chopped. As the dimmer 112
is dimmed, such as by moving its control 124, increasing portions
of the sine wave are chopped. For example, as shown in FIG. 2A, the
sine wave has been chopped a small amount, dimming the power output
about 10%. In FIG. 2B, the sine wave has been chopped a moderate
amount which dims power output a moderate amount around 50%. In
FIG. 2C, the sine wave has been chopped a large amount, dimming the
power output a large amount around 85%.
It is noted that various dimmers 112, now known or later developed
may be used with the dimmable LED driver 104. This is advantageous
in that it allows the dimmable LED driver 104 to be used with phase
and other dimmers 112 commonly found in existing buildings. In
addition, it is contemplated that the dimmable LED driver 104 may
be used with any dimmer or similar device that chops or alters an
AC signal as described herein.
The AC signal from the dimmer 112 may be received by the dimmable
LED driver 104, as can be seen from FIG. 1. As will be described in
the following, the dimmable LED driver 104 may utilize the timing
(rather than power level) of the AC signal to determine the desired
level of light and to provide an output which provides this level
of light from one or more LED bulbs 108.
Operation of the dimmable LED driver 104 will now be described with
regard to FIGS. 3A-3C. As stated, in one or more embodiments, the
dimmable LED driver 104 utilizes the duty cycle (rather than power
level) of an AC signal to determine the desired level of light
output. This may occur in various ways. In one or more embodiments,
the LED driver 104 may detect a pulse width T.sub.on of one or more
pulses in an AC signal, and the period P of the AC signal. The
ratio of the pulse width T.sub.on and period P of the AC signal may
then be used to determine the desired level of light. It is noted
that the ratio between the sum of a plurality of pulse widths and a
period of an AC signal may be used as well. For example, the ratio
of the sum of two pulse widths to the period of an AC signal may be
used to determine the desired level of light where two pulses occur
within the period of the AC signal.
In one or more embodiments, the LED driver 104 may have one or more
preset values for the period P. For example, the period P may be
set to an expected, known, and/or standardized frequency of an AC
power source. To illustrate, period P may be set to a standardized
frequency such as 50 Hz in Europe or 60 Hz in North America. Modern
utilities supply AC power very close to or at the standardized
frequencies and thus the period P may be set to a preset value
rather than detected/determined by the LED driver in these
embodiments. The LED driver 104 may store the preset value or
values in a memory device or be hardwired with one or more preset
values.
It is contemplated that in embodiments where a plurality of preset
values are provided, the LED driver 104 may be configured to select
a preset value for the period P based on a detected period for the
AC signal. For instance, the LED driver 104 may be configured to
determine a period of the AC signal and set the period P to a
preset value accordingly. In one embodiment, the LED driver 104 may
set the period P to the preset value closest to the detected period
of the AC signal. This allows the LED driver 104 to be used with
power sources of various frequencies without the need for manual
configuration.
It is noted that the period P need only be set to a preset
frequency value once. This is because the frequency of an AC signal
typically remains constant. Of course, the LED driver 104 may
periodically take a measurement of the AC signal to confirm the
period P is set to the correct preset, and, if necessary, switch to
different preset when appropriate. For example, the LED driver 104
may take a measurement of the AC signal the first time or each time
the LED driver is turned on (i.e. AC power is supplied to the LED
driver) in some embodiments.
In general, and as will become apparent from the discussion herein,
the dimmable LED driver 104 utilizes the timing of an AC signal,
such as its pulse width T.sub.on and period P, to determine the
desired level of light output. Once the desired level of light is
determined, an output signal may be generated to provide a
corresponding level of light from one or more LEDs, LED bulbs, or
other LED lighting.
FIGS. 3A-3C illustrate exemplary AC signals which the dimmable LED
driver 104 may receive. Similar to FIGS. 2A-2C, the AC signals in
these figures show altered or chopped AC signals which correspond
to various levels of dimming. It is noted that these altered AC
signals are exemplary and the dimmable LED driver 104 may operate
with various AC signals having greater or lesser chopped portions.
Also, it will be understood that the dimmable LED driver 104 may
utilize various sinusoidal signals in one or more embodiments.
FIGS. 3A-3C illustrate a threshold V.sub.t and a pulse width
T.sub.on which may be used in determining the desired amount of
dimming indicated of an AC signal. The pulse width T.sub.on as used
herein will be a measurement of time. The threshold V.sub.t allows
a pulse width T.sub.on to be determined for one or more pulses of
an AC signal. As can be seen, the pulse width T.sub.on may be
delineated by the points where the voltage of the AC signal cross
the threshold V.sub.t. In general, a pulse width T.sub.on may be
delineated by a first point and a second point on the threshold
V.sub.t. In this manner, the time between the first point and the
second point may indicate the pulse width T.sub.on of a pulse. The
first point may be where the voltage of the AC signal is increasing
as it crosses the threshold V.sub.t, and the second point may be
where the voltage is decreasing as it crosses the threshold
V.sub.t. To illustrate, as can be seen in FIG. 3A, the pulse width
T.sub.on is delineated by the points where the AC signal's voltage
increase to cross the threshold V.sub.t and decrease to cross the
threshold V.sub.t. Of course, the first point may be where the
voltage of the AC signal decreases across the threshold V.sub.t
while the second point may be where the voltage increases across
the threshold V.sub.t. It is noted that typically, but not always,
the first and second point will occur within a phase angle of 0 to
180 degrees of the AC signal.
Similarly, the period P of the AC signal may be determined by one
or more points on the threshold V.sub.t where the voltage of the AC
signal increases to cross the threshold V.sub.t or decreases to
cross the threshold V.sub.t. For example, two (or more) consecutive
points on the threshold V.sub.t where the AC signal's voltage
increases to cross V.sub.t may be used to determine the period of
the AC signal. Likewise, two consecutive points on the threshold
V.sub.t where the AC signal's voltage decreases as it crosses
V.sub.t may be used to determine the period of the AC signal. As
can be seen from FIG. 3A, the period P of the AC signal may be
determined by two consecutive points on V.sub.t where the voltage
is increasing as it crosses V.sub.t.
It is noted that various methods of determining the period of an AC
signal may be used. It is contemplated that these methods, now
known or later developed, may be used by the dimmable LED driver
104 to determine the period of an AC signal.
The threshold V.sub.t may be set to various voltages. In one
embodiment, V.sub.t may be a positive or negative voltage. It is
contemplated that in general, the threshold V.sub.t will be set
such that the voltage of an AC signal will cross the threshold
V.sub.t at an interval which allows a pulse width T.sub.on and
period P of the AC signal to be accurately measured as discussed
herein.
As shown in FIGS. 3B and 3C, as increasing portions of the AC
signal are chopped, the pulse width T.sub.on is reduced while the
period P of the AC signal remains the same. This allows a
comparison or ratio between pulse width T.sub.on and period P to be
used to determine the desired amount of dimming. To illustrate, in
FIG. 3A, it can be seen that a small amount of dimming is desired
as shown by the chopping of about 10% of the AC signal.
Accordingly, pulse width T.sub.on is relatively large when compared
to period P. In FIGS. 3B and 3C, pulse width T.sub.on decreases
relative to period P as increasing amounts of the AC signal are
chopped. In FIG. 3B, pulse width T.sub.on represents a pulse width
of an AC signal that has been dimmed about 50%, while in FIG. 3C,
T.sub.on represents a pulse width for an AC signal dimmed about
85%.
As stated, the amount of dimming desired may be determined by the
ratio of a pulse width T.sub.on to period P. For example, the
formula T.sub.on/F may be used in one or more embodiments to
determine the percentage of dimming desired. This may be multiplied
by a factor of two to reflect the fact that there may be two pulses
within the period of the AC signal. For example, the pulse width
T.sub.on in FIGS. 3A-3C is measured using only the positive pulses
of the AC signal. It is noted that various other factors may be
used to compensate for other aspects of the AC signal as well. For
example, in one embodiment, an offset may be used to compensate for
the voltage at which the threshold V.sub.t is set.
Applying the ratio of pulse width T.sub.on to period P in FIG. 3A,
it can be seen that the alteration(s) to an AC signal's duty cycle
by a dimmer can be detected and the corresponding desired level of
light output determined. In the example provided by FIG. 3A, the
formula
##EQU00001## may be used to determine the desired level of light
output as a percentage. Assuming example values of 45 for T.sub.on
and 100 for P (as measures of time), the desired level of light
output would be determined at 90%.
It is noted that the amount of light output may be determined on a
nonlinear curve based on pulse width T.sub.on and/or period P in
one or more embodiments. For example, the amount of light output
may be a square, cube, or other nonlinear function. This is
advantageous in that it allows the LED driver 104 to compensate for
the way light levels are perceived by a viewer. In general, changes
in brightness are perceived nonlinearly by human observers. For
example, a change in light output of a bright light is not as
noticeable as a change in light output a dim light. Thus,
outputting levels of light along a curve can be used to produce a
smoother transition from maximum output to minimum output. For
instance, at higher output levels, light may be dimmed a larger
amount because changes in brightness at high output levels are not
as easily perceived.
In one exemplary embodiment, the amount of light output may be
determined by the nonlinear function
##EQU00002## where V.sub.o and A may be values used to offset
characteristics of the AC signal or LED driver 104 so that the
desired level of light may be accurately provided. Of course, A may
be set to 1 and V.sub.o set to 0 if such offsetting is not desired.
As can be seen, the light output is along a curve according to this
square function which compensates for nonlinearities in the
perception of light levels.
Once the desired amount of dimming has been determined and output
may be provided to power one or more LEDs in a manner that provides
the desired level of light output. Various methods, now known or
later developed, may be used to provide an electrical output which
controls the level of light provided by an LED. For example, known
methods such as pulse width modulation, or altering current or
voltage provided to an LED may be used.
Various embodiments of dimmable LED drivers 104 which allow full
range LED dimming utilizing the timing of an AC signal will now be
described with regard to FIGS. 4A-4C. It will be understood that
other configurations of the LED driver which accept and measure the
timing characteristics of an AC signal, as discussed above, to
determine the amount of dimming a user desires may be constructed
as well. In addition, it is noted that, though described with
particular sets of components, components having the same of
similar function may be used in one or more embodiments to
determine the amount of desired dimming by the timing of a dimmed
AC signal. It will be understood that portions of the various
embodiments herein may be utilized in one or more combinations to
perform the functions of a dimmable LED driver as described
herein.
FIG. 4A illustrates a block diagram of an exemplary dimmable LED
driver 104. In this embodiment, the dimmable LED driver 104
comprises a signal processor 428 and a controller 412. The signal
processor 428 receives an AC signal from an input 416 while the
controller 412 provides an output signal to one or more LEDs via an
output 420. In one or more embodiments, the input 416, output 420,
or both may be an electrical conduit, coupling, or other electrical
connection or connector.
In general, the signal processor 428 processes an AC signal to
provide a signal usable by the controller 412 to determine the
desired level of light output. In one or more embodiments, the
signal processor 428 processes the AC signal so that one or more
pulse widths and a period of an AC signal may be determined by the
controller 412. For example, the signal processor 428 may provide a
pulse train where the pulses represent one or more pulse widths of
an AC signal, and the timing of the pulses represents a period of
the AC signal. As will be described below the signal processor 428
may have various components and be constructed in various ways.
The controller 412 may then utilize this signal to determine the
desired level of light output based on one or pulse widths and a
period of the AC signal. For example, the controller 412 may
utilize a ratio of one or more pulse widths to the period of the AC
signal to determine the desired level of light output, such as
described above.
The controller 412 may be constructed in various ways. In one or
more embodiments, the controller 412 may comprise a circuit,
microprocessor, ASIC, FPGA, control logic, or the like. In some
embodiments, the controller 412 may execute instructions to
calculate or otherwise determine the desired level of light based
on pulse widths and periods of an AC signal. The instructions may
be hard wired into the controller, such as through control logic,
or may be stored in a memory device for retrieval and execution by
the controller.
As discussed above, one or more factors to the calculation of
desired level of light output in some embodiments. The controller
412 may be configured to perform this function. For example, where
two pulses occur within the period of an AC signal, the controller
412 may apply a multiplication factor of two, such as described
above. In this manner, the controller 412 compensates for the
number of pulses per period in the AC signal. Of course, as stated,
various other factors as well as offsets may be used or included.
In addition, the calculation of desired level of light output may
occur according to various formulas and, as stated above, may be
nonlinear to compensate for nonlinearities in perception of light
levels by the eye. Typically, but not always, the desired level of
light output will be determined or calculated as a percentage (e.g.
0% to 100%) light output. Once the desired level of light output is
determined, the controller 412 may generate an output signal
indicating the desired level of light output.
The controller's output signal may be communicated or provided via
an output 420 to one or more external components or devices. For
example, it is contemplated that the output signal may be provided
to one or more LEDs to provide the desired level of light. In the
embodiment of FIG. 4A, the output signal is provided to another
component. As can be seen, the output signal is provided to a
driver 432 in the embodiment of FIG. 4A.
In general the driver 432 processes the controller's 412 output
signal so that the output signal may be used to provide the desired
level of light from one or more LEDs 108. For example, in one
embodiment, the driver 432 may amplify the output signal to power
one or more LEDs at the desired light level. The driver 432 may
also convert the output signal into a pulse width modulation signal
to provide the desired level of light from one or more LEDs.
Alternatively, or in addition, the driver 432 may modify the
current or voltage of the output signal to achieve the desired
level of light from one or more LEDs. It is contemplated that the
driver 432 may utilize various methods, now known or later
developed, to power one or more LEDs in a manner which produces the
desired level of light as determined by the controller 412.
It is noted that a driver 432 may not be provided in all
embodiments. For example, the controller 412 or other component of
the dimmable LED driver 104 may perform the function of a driver
432. In addition, in some situations, the controller's 412 output
signal may be used to power one or more LEDs in a manner which
produces the desired level of light without further processing by a
driver 432 or other component.
It is also noted that the controller 412 may determine the desired
level of light without a signal processor 428 in some embodiments.
For example, the controller 412 itself may accept an AC signal and
determine one or more pulse widths and period of the AC signal
without the AC signal first being processed by the signal processor
428. It is further noted that in some embodiments, the signal
processor 428 may be internal to the controller 412. In these
embodiments, a separate signal processor 412 may not be
required.
FIG. 4B illustrates a block diagram of an exemplary dimmable LED
driver 104 comprising a rectifier 404, comparator 408 and
controller 412. In this embodiment, the signal processor 428
comprises a rectifier 404 and comparator 408. It will be understood
that the signal processor 428 may perform its AC signal processing
function with different components however.
The dimmable LED driver 104 may also comprise an input 416 to
accept the AC signal, and an output 420 to provide an output signal
such as described above. Though not shown, a driver may be
connected to the output 420 to process the output signal, if
necessary or desired. As shown, a voltage reference 424 may be
provided for comparison of various signals as will be described
below.
In this embodiment, an AC signal may be received at the input 416.
The signal may be rectified by a rectifier 404 to convert the AC
signal into a pulse train. Exemplary pulse trains are illustrated
in FIGS. 5A-5C and will be described further below. In some
embodiments, a full wave rectifier 404 may be used so that the
positive and negative portion of an AC signal are converted into a
pulse train. Of course, a half wave rectifier 404 may be used as
well. As stated above, an AC signal from a dimmer will typically
comprise a sine wave chopped at the same location for a particular
level of dimming. Thus, the dimmable LED driver 104 need not
measure every pulse to determine the desired level of dimming. The
measurement of one or some pulses may be sufficient to determine
the desired level of dimming. For these reasons, the dimmable LED
driver 104 may utilize a full wave rectifier 404 or a half wave
rectifier. The selection of full wave or half wave rectifiers 404
may be for various reasons including cost, efficiency, or other
characteristics of the rectifiers.
As indicated above, FIGS. 5A-5C illustrate the exemplary AC signals
of FIGS. 2A-2C after rectification by a half wave rectifier. It can
be seen that the positive portion of the AC signals of FIGS. 2A-2C
have been converted by rectification into a corresponding pulse
train in FIGS. 5A-5C. It can also be seen that the pulses generally
have the same size and shape as the original AC signal except that
the rectification process has given the pulse train a uniform
polarity. As is known, half wave rectification results in a pulse
train only including the positive or negation portion of the
original AC signal. The pulse train would include the positive and
negative portion of the original AC signal if full wave
rectification were used. It will be understood that the dimmable
LED driver may utilize positive or negative pulse trains in
operation.
Referring back to FIG. 4B, the rectified signal may then be
received by a comparator 408. In general, the comparator 408
compares the pulse train of the rectified AC signal with a voltage
threshold provided by a voltage reference 424. The voltage
threshold provided will typically be a substantially constant
voltage which the comparator 408 may compare to voltages of the
pulses or signals it receives from the rectifier 404. The voltage
threshold may also be a function of the AC input signal in one or
more embodiments. Where the voltage of a pulse is above the voltage
threshold, the comparator 408 may output a first signal. When the
voltage of the pulse is below the voltage threshold, the comparator
408 may output a second signal, different from the first signal. In
one or more embodiments, the second signal may be 0V or a low
voltage and the first voltage may be a higher voltage, or vice
versa. Of course, the comparator may alternatively output the
second signal for voltages higher than the voltage threshold, and
output the first signal for voltages lower than the voltage
threshold.
The operation and output of a comparator 408 can be seen in FIGS.
3A-3C which have been described above. As shown, an exemplary
voltage threshold V.sub.t may be used to compare the voltage of one
or more pulses. The threshold V.sub.t will typically be the voltage
provided by the voltage reference 424. It is contemplated that an
offset may be utilized to adjust the voltage provided by the
voltage reference 424 if desired. For example, the threshold
V.sub.t may be raised or lowered relative to the voltage of the
voltage reference 424 by a positive or negative offset.
As can be seen with reference to FIGS. 3A-3C, the comparator 408
generates a first output when the voltage of a pulse crosses above
voltage threshold V.sub.t. A second output is generated when the
voltage of a pulse crosses below V.sub.t. In this embodiment, the
first output is a fixed voltage representing the pulse width
T.sub.on. The second output may be zero volts or other lower
voltage. As can be seen, the output from the comparator results in
a square wave having one or more square pulses, the edges of which
correspond to the pulse width T.sub.on of the pulses received from
the rectifier. Thus, it can be seen that pulse width T.sub.on of
these pulses may be determined by the time between the edges of the
one or more square pulses.
It is noted that the first output and second output may be various
signals including the fixed voltage output described above. In
fact, as long as the first output and second output are
distinguishable, a rectifier pulse (and thus the desired amount of
dimming) may be measured by a dimmable LED driver 104 or component
thereof as described herein.
As can be seen from FIG. 4B, the controller 412 may receive the
output of the comparator 408. It is noted that some controllers 412
may internally include a comparator and that in these embodiments a
separate comparator may not be provided. The controller 412 may
determine the desired amount of dimming by determining a pulse
width T.sub.on and period P from the comparator's 408 output, and
provide an output signal which may then be used to produce the
desired level of light from one or more LEDs directly or through
one or more components, such as a driver as described above.
In one or more embodiments and as described above, pulse widths
T.sub.on may be represented by the square pulses of a comparator's
square wave output. Thus, in these embodiments, the controller 412
may utilize the duration of a square pulse in the square wave
output as a pulse width T.sub.on. Stated differently, the time
between the leading and trailing edges of a square pulse may be
used as a pulse width T.sub.on measurement.
Period P may generally be determined by the distance between two or
more square pulses. For example, the time between the trailing or
left edges of the square pulses in FIG. 3A indicate the period P of
the AC signal. It will be understood that other corresponding
portions of (at least) two square pulses may be used to determine
the period P as well. For example, the time between the leading or
right edge of two square pulses may be used to determine period
P.
Once pulse width T.sub.on and period P of an AC signal have been
determined, the controller 412 may compare one or more pulse widths
T.sub.on to the period P of the AC signal to determine the desired
amount of light output. The ratio of a pulse width T.sub.on to the
period P may then be used to determine the desired amount of light
output. As stated above, period P may be a preset value in one or
more embodiments. In these embodiments a preset period P may be
used to determine the desired amount of light output.
Once the desired level of light output has been determined, the
controller 412 may provide an output signal via the output 420. The
output signal may be processed, such as by the controller 412
itself or by a driver, to provide various levels of light from an
LED. For example, as stated, known methods such as pulse width
modulation or current change may be used to control the level of
light from an LED. It is contemplated that a change in voltage may
also or alternatively be used to control the level of light as
well.
In some embodiments, the dimmable LED driver 104 may not include a
comparator. FIG. 4C illustrates such an embodiment where the signal
processor 428 does not utilize a comparator. The controller 412 may
still determine pulse width and period of an AC signal in these
embodiments in various ways. In one embodiment an AD (analog to
digital) converter within the controller 412 may be used to
determine when the voltage of an AC signal is above or below a
voltage threshold. In addition or alternatively, the controller 412
may be connected to a voltage reference 424 or utilize an internal
voltage reference. The controller 412 may then compare voltages of
the pulses from the rectifier 404 to a voltage threshold V.sub.t
provided by the voltage reference 424. This allows the controller
412 to determine one or more pulse widths T.sub.on delineated by
one or more points where voltages of the pulses cross the voltage
threshold V.sub.t, such as described above with regard to FIGS.
3A-3C.
As can be seen from FIGS. 3A-3C, these points also delineate one or
more pulses in the AC signal. The time between corresponding
portions of at least two of the pulses may be used to determine the
period P of the AC signal. For example, the period P of an AC
signal may be determined by the time between the leading or
trailing edges of (at least) two pulses. A correct preset value for
period P (e.g. 50 Hz or 60 Hz) may also be determined in this
manner. Alternatively, the period P may be set to a preset value,
such as 50 Hz or 60 Hz for example, which removes the need to
determine the period P in one or more embodiments. The ratio of the
pulse width T.sub.on to this period P may then be used to determine
the desired level of light output.
It is noted that in some embodiments, the controller 412 may also
perform the function of a rectifier 404 or include a rectifier. In
these embodiments, a separate rectifier may not be provided. In
addition, it is contemplated that a rectifier 404 may not be
necessary in all embodiments because the controller 412 may be
configured to ignore portions of an incoming AC signal. For
example, the controller 412 may ignore portions of an AC signal
below a threshold. In one embodiment, portions of an AC signal
below 0V may be ignored. This causes the controller 412 to only
operate on the positive pulse train consisting of the portions of
the AC signal above 0V. This is similar, if not identical, to the
pulse train that would have been provided by a half wave rectifier.
Thus, it can be seen that a rectifier 404 may not be required in
all embodiments.
From the above, it will be understood that determining the desired
amount of dimming through the timing of an AC signal provides an
accurate determination of the desired amount of dimming regardless
of the power level, voltage, or current of an AC signal. This is
generally because the ratio of the pulse widths in a dimmed AC
signal to the period of the AC signal provides an independent way
of measuring the amount of dimming and consequently the desired
amount of light output. In this manner, the desired amount of
dimming can be accurately determined even when power levels in an
AC signal fluctuate or change. Such fluctuations or changes to
power level can be common and may be caused by changes to power
output by a utility company or by turning on or off electrical
devices. Because the dimmable LED driver does not rely on power
level to determine the desired amount of dimming, the dimmable LED
driver can provide full range dimming where traditional drivers
cannot, as discussed above.
Further, it can be seen that the LED driver may also compensate for
changes in the period of an AC signal. In one or more embodiments,
a change in the period of an AC signal may be detected by an
increase or decrease in the distance between pulses. Thus, even if
the period changes the determination of the desired amount of light
output remains accurate. In addition, it is noted that the ratio
between pulses of a dimmed AC signal to the period of the AC signal
may remain substantially constant as the period changes. For this
reason, the determination of desired light output by the dimmable
LED driver remains accurate.
The ability of the dimmable LED driver to use the timing of an AC
signal to determine the desired level of light output also reduces
or eliminates the need to calibrate the dimmable LED driver for
various AC standards. Of course, the dimmable LED driver must be
configured to accept the voltages or currents it is provided, but
it need not be calibrated or set for specific voltages or currents
or specific voltage or current ranges. This is because timing and
not power level of an AC signal is used to determine desired light
output. In addition, the dimmable LED driver need not be configured
for AC signals of particular frequencies or particular ranges of
frequencies. As discussed above, the period of an incoming AC
signal may be detected by the dimmable LED driver and used to
provide accurate full range dimming of an LED.
The dimmable LED driver may be used in a variety of applications.
In one or more embodiments, the dimmable LED driver may be
relatively small in size. This allows the dimmable LED driver to be
installed in various locations and devices large and small. FIGS.
6A and 6B illustrate example devices and locations where a dimmable
LED driver 104 may be installed. FIG. 6A is a cross section view of
a dimmable LED driver 104 is mounted to a standard overhead
lighting can 604. An AC signal from a phase dimmer or the like may
be provided via standard wiring to the dimmable LED driver 104. The
dimmable LED driver 104 may have its outputs connected to a socket
608 which accepts an LED bulb 108. In this manner, full range
dimming of the LED bulb 108 can be achieved through a standard
phase dimmer.
It is noted that because the wiring from the phase dimmer to the
lighting can 604 is the same as the wiring for incandescent
lighting, the dimmable LED driver 104 allows easy retrofit of
existing lighting systems. For example, an incandescent lighting
can may be replaced with the lighting can 604 described above
having a dimmable LED driver 104 attached thereto. In addition, or
alternatively, a dimmable LED driver 104 may be connected to the
socket of an existing lighting can to allow dimming of an LED bulb
via the now enhanced socket.
FIG. 6B illustrates a LED bulb 612 having a dimmable LED driver 104
built in. In this embodiment, the dimmable LED driver 104 may be
located in the base portion of the LED bulb 612. This is highly
advantageous in that fully dimmable LED lighting may be installed
simply by replacing an incandescent or other bulb with this LED
bulb 612. In one or more embodiments, the LED driver's input will
accept an AC signal from the LED bulb's screw-type or other
connector and provide output to one or more LEDs within the LED
bulb 612.
As another example, the dimmable LED driver may be built into a
standard phase dimmer. In this embodiment, by replacing a standard
phase dimmer and installing an LED bulb in the appropriate socket,
fully dimmable LED lighting may be achieved. In one or more
embodiments, the input of the dimmable LED driver may be connected
to an output of the phase dimmer and the output of the driver
connected to wiring which leads to a socket for holding the LED
bulb.
It can thus be seen that the dimmable LED driver provides numerous
advantages and may be used in many different ways. By providing
full range dimming for LEDs, the dimmable LED driver allows LED
lighting to be used in applications where high quality dimming is
required or desired. This allows users to take advantage of the
efficiency and reliability benefits of LED lighting while allowing
accurate and full range dimming which is not provided by
traditional LED drivers.
While various embodiments of the invention have been described, it
will be apparent to those of ordinary skill in the art that many
more embodiments and implementations are possible that are within
the scope of this invention. In addition, the various features,
elements, and embodiments described herein may be claimed or
combined in any combination or arrangement.
* * * * *